docs: def encrypt_metadata(keys, fileName, fileType='application/octet-stream'):
      '''Encrypt file metadata with the same method as the Send browser/js client'''
      metadata = json.dumps({'iv' : unpadded_urlsafe_b64encode(keys.encryptIV), 'name' : fileName, 'type' : fileType}, sort_keys=True)
  
      cipher = Cryptodome.Cipher.AES.new(keys.metaKey, Cryptodome.Cipher.AES.MODE_GCM, keys.metaIV)
      encMeta, gcmTag = cipher.encrypt_and_digest(metadata.encode())
  
      # WebcryptoAPI expects the gcm tag at the end of the ciphertext, return them concatenated
      return encMeta + gcmTag